For decades, scientists and sea explorers have mounted costly expeditions to hunt down and photograph the giant squid, a legendary monster with eyes the size of dinner plates and a nightmarish tangle of tentacles lined with long rows of sucker pads.

The goal has been to learn more about a bizarre creature of no little fame – Jules Verne's attacked a submarine and Peter Benchley's ate children – that in real life has stubbornly refused to give up its secrets.

While giant squid have been snagged in fishing nets and dead or dying ones have washed ashore, expeditions have repeatedly failed to photograph a live one in its natural habitat, the inky depths of the sea.

But today, two Japanese scientists, Tsunemi Kubodera and Kyoichi Mori, report in a leading British biological journal that they have made the world's first observations of a giant squid in the wild.

Working about 600 miles south of Tokyo off the Bonin Islands, known in Japan as the Ogasawara Islands, they managed to photograph the creature with a robotic camera at a depth of 3,000 feet. During a struggle lasting more than four hours, the 26-foot-long animal took the proffered bait and eventually broke free, leaving behind an 18-foot length of tentacle.

The giant squid, the researchers conclude, "appears to be a much more active predator than previously suspected, using its elongate feeding tentacles to strike and tangle prey." They report that the tentacles could apparently coil into a ball, much as a python envelops its victims.

The Japanese researchers are reporting their find today in the Proceedings of the Royal Society B, the "B" standing for the biological sciences. The Royal Society, based in London, is the world's oldest scientific organization.

Scientists praised the discovery as a long-awaited breakthrough.

"This has been a mystery for a thousand years," said Richard Ellis, author of "Monsters of the Sea." "Nobody knew what they looked like in the wild. We only saw them dead. These images will open the door to more detailed study of their life."

The Japanese researchers work for the National Science Museum in Tokyo and the Ogasawara Whale-Watching Association.

They discovered the giant by following packs of sperm whales, which are known to feed on the giant squid. With squid remains being found near the Bonin Islands, the researchers focused their hunt there.

At an estimated size of 26 feet, this is a relatively small specimen; giant squid are thought to grow as long as 60 feet. But with DNA analysis and other comparisons with squid that have washed ashore, the researchers confirmed that it was a giant.